SPIN-LOCK FIELD-CYCLING IMAGING RELAXOMETRY

Spin-lock adiabatic field-cycling imaging (SLOAFI) relaxometry is a no vel principle for the fast and convenient record of the dependence of the rotating-frame spin-lattice relaxation time T-1 rho on the effecti ve frequency. A spatial distribution of effective frequencies is produ ced by adiabatically varying the effective-frequency offset in the pre sence of a B-o or a B-1 gradient. The spin-locked magnetization relaxe s according to the local values of the effective frequency. The profil e of the partially relaxed magnetization is imaged using either labora tory-frame (B-1-gradient based) or rotating-frame (B-1-gradient based) imaging. The T-1 rho dispersion can then be evaluated from a series o f magnetization profiles recorded while incrementing the relaxation in terval. B-0-gradient SLOAFI relaxometry was applied to melts of polydi methylsiloxane. The frequency dependence obtained with conventional te chniques could be reproduced. (C) 1995 Academic Press, Inc.